After installing Opus 9 on a Sony Vaio Laptop with a 19" widescreen display running Vista Home Prermium, all new windows (eg Windows Explorer, Word, Outlook etc) no longer fill the screen. Instead, they occupy the left side of the display even when maximised.
I have been through all the display settings, and can't find a way of changing this. I have done a system restore back to pre- Opus9 and everything is back to normal, so for example when I open Windows Explorer, it now fills the screen left to right and top to bottom.
It sounds like you have an Opus toolbar docked to the side of your screen, maybe also set to appear transparent so that it isn't obvious it is there.
Go to Settings -> Customize -> Toolbars and select each of the toolbars that is ticked in the list. For each one, see if the Floating Toolbar option on the right is also ticked. If it is, close that toolbar by clearing the tick beside its name in the list.
Another thing to try: Select Tools -> Output Window to open the output window, and then select it again to close it. The output window is another part of Opus which can "dock" to the side of the screen. I think that and floating toolbars are the only things in Opus which can do that.